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Virtual functions is a function that can be overridden in inheriting class with the same signature (function name, parameters number, parameters types and return type);
Pure virtual function is function that does not have implementation and if class has pure virtual function is called abstract. It is not possible to instantiate that class. Some other class must inherit it and define the body for it (implement). In other words class only have function prototype/declaration(signature) and no definition(implementation).
What else can I help you with?
How do you represent a C plus plus non-pure virtual function in UML?
All virtual functions (including pure-virtual functions) are represented in italics. All non-virtual functions are represented normally. There is no differentiation between pure and non-pure virtual functions, however some people append "=0" to distinguish the pure-virtual functions.
What is the difference between virtual function and function overriding?
Virtual Functions and Pure Virtual Functions are relevant in the context of class inheritance.Unlike Virtual Functions, Pure Virtual Functions do not require a body. This implies that when a base class defining such a function is inherited, the derived class must implement that function. Furthermore, the base class becomes abstract; meaning you cannot create an instance of the base class even if a body is implemented for the function. You are expected to derive from abstract classes; only the derived classes that implement all the inherited Pure Virtual functions can be instantiated.Here are some examples of Virtual and Pure Virtual function signatures:- Virtual Function: E.g. virtual void myFunction();- Pure Virtual Function: E.g. virtual void myFunction() = 0;
Can you have inline virtual functions in a class?
No, inlining is done at compile time whereas virtual functions are resolved at run time(late binding). So, virtual functions can't be inlined. Both properties are orthogonal.Inlining is a mere suggestion the compiler may ignore it if it is declared with virtual function.
A pure virtual function is a virtual function that has?
A pure-virtual function is a function that must be overridden in derived classes. You simply add "=0" to the end of the function declaration. class AbstractClass { public: virtual void DoSomething()=0; // Pure-virtual. };
When do we make a virtual function pure?
We make a virtual function pure whenever we wish to make our class an abstract base class (an abstract data type). Unlike a virtual function, pure virtual functions must be overridden by a derived class or by one of its derivatives (the function remains pure virtual until it is overridden, at which point it becomes virtual). Derived classes that do not provide a complete implementation for all the pure virtual functions it inherits become abstract themselves. You cannot instantiate an abstract base class other than through derivation.
How dynamic binding acheived in c plus plus?
Dynamic binding is achieved via virtual functions and the virtual table that is associated with every class that declares or inherits a virtual function. The virtual table (or v-table) maps every virtual function (including pure-virtual functions) to a function pointer that points to the most-derived overload. This makes it possible to invoke specific behaviour even when the runtime type of the object is unknown to the caller.
What is a pure virtual member function in c plus plus?
Functions in C++ are separate procedures or subroutines within a program, that can be called as often as required and which can return values back to their callers. That is, when you make a function call, execution passes to the function and then returns to the caller. Functions that are class members are also known as member functions, member methods, or simply methods. These work exactly the same as external functions except they are scoped to the class and have access to private members of the class.
What are the implecations of making a function pure virtual function?
Only class instance methods can be rendered as pure-virtual functions (or pure-virtual methods, to be precise). Non-member functions and static member methods cannot be declared pure-virtual.The implication of declaring a pure-virtual function is that the class to which it is a member becomes an abstract data type (or abstract base class). This means you cannot instantiate an object of that class, you can only derive classes from it. Moreover, the derived classes must also implement the pure-virtual functions or they, too, become abstract data types. Only concrete classes that contain a complete implementation can be instantiated, although they can inherit implementations from their base classes (but not from the class that initially declared the method).Pure-virtual functions ensure that you do not instantiate base class objects that are not intended to be instantiated (they are conceptual rather than actual objects) and that derived objects provide a specific implementation. Typically, all methods of an abstract base class will be declared pure-virtual to ensure correct behaviour in derived classes through a common interface. Abstract base classes will also have few member variables, preferably none at all.For example, a shape is a conceptual object whereas a rectangle, triangle or circle are actual objects. As such they can all be derived from shape. The shape base class need only declare the interface that is common to all shapes, such as Draw(), Rotate(), Mirror() and so on. But since a shape doesn't have enough information to implement these methods, they must be declared pure-virtual. This ensures that shape cannot be instantiated (since it would be meaningless) and that every object derived from shape not only has a common interface, but that each type of shape provides its own specific implementation of those methods. This is not unlike overriding standard virtual functions, however the difference is that you must override the pure-virtual methods; it is not optional unless the derived class is intended to become abstract itself.
Explain a pure virtual function with an example?
There are no pure virtual functions, but there are pure virtual function calls.In C++, classes can define abstract functions. Those are virtual functions for which no implementation is supplied in the class that defines it. Abstract functions are typically used to define a contract. For example, a base class for any vehicle might guarantee that a move() method exists, but only classes derived from vehicle implement this method according to the properties of the specific vehicle: a bike, a car, a skateboard, etc. Classes containing abstract functions are sometimes called abstract classes.The C++ compiler does not allow the creation of an object of type vehicle in this example, because the vehicle class contains an abstract function.Classes derived from vehicle (derived in first or higher degree) must supply an implementation of this method before the compiler allows the creation of an object of this type.Therefore, any valid object descended from vehicle must have an implementation of the move method. However, since it is possible to create pointers to abstract classes (classes that contain abstract functions which have not yet been given an implementation), pure virtual function calls can occur at runtime.Consider this example:class vehicle {public:virtual void move(void) = 0; // abstract function};class motorizedVehicle : vehicle {...};class car : motorizedVehicle {public:virtual void move(void) {... // implementation}};An application cannot create objects of type vehicle or motorizedVehicle, but it can create pointers to those. Those might give access to classes that have no implementation for the move method, and calling it results in a run-time diagnostic known as a pure virtual function call.
What is virtual function table?
A virtual function table is a table of pointers to functions.
Which binding virtual function used?
Virtual functions are dynamically bound at runtime.
What is a Pure Virtual Function Write a C plus plus program using Pure Virtual Function?
A pure-virtual method is similar to a virtual method. A virtual method is a method that is expected to be overridden in a derived class while a pure-virtual method must be overridden in a derived class. The base class may provide a default implementation for a pure-virtual method, but it is not a requirement, whereas it must provide an implementation for a virtual method. In addition,any base class that has a pure-virtual method becomes abstract; you cannot instantiate abstract classes -- you are expectedto derive from them.#include class Abstract{public:// Pure-virtual method; note the '=0' to denote pure-virtual.virtual void Show()=0;};class Derived : public Abstract{public:virtual void Show(){// Implementation is required here!std:: cout
